Process for Peristaltic Pump Control

ABSTRACT

A peristaltic pump is provided comprising squeezing elements moved by at least one actuator, which squeezing elements act on a tube in which a medium is conveyed, with the squeezing elements successively getting into and out of a squeezing engagement with the tube. A process for controlling the peristaltic pump comprises measuring over time a fluidic parameter representative for the flow rate of the medium through the tube, determining the relative undulation of the flow rate of the medium from the measured temporal course of the fluidic parameter, and smoothing the undulation by adjusting the progression speed of the squeezing elements on the basis of the determined undulation of the flow rate.

BACKGROUND OF THE INVENTION

The present invention is directed to peristaltic pumps and, in particular, to a process for peristaltic pump control.

Peristaltic pumps are displacement pumps in which the medium to be conveyed is guided through a tube which, in most cases, is U-shaped, but may also be linear or arranged along largely any path. Said tube is supported in the body of the pump and is pinched successively by squeezing elements such as rolls or sliding blocks, which are moved by an actuator. Said actuator is usually designed as a rotor. The rotation of the rotor moves the pinched point generated by the squeezing elements along the tube and thus pushes forward a volume of the medium to be conveyed in the tube, which volume is located ahead of the pinched point. Simultaneously, a negative suction pressure is generated at the tube inlet. In alternative embodiments of peristaltic pumps, the actuators are designed as linear drives, or a plurality of squeezing elements are consecutively arranged along the tube—in the manner of a piano keyboard—and are each pressed in succession against the tube by a separate actuator so that a kind of progressive motion develops. The essential advantages of peristaltic pumps are a careful transport of sensitive materials to be conveyed, a completely closed system, absence of valves, a possibility of conveying media with solid particles and precise dosability of outputs. Because of those properties, peristaltic pumps are frequently used in laboratory equipment, e.g., in blood analysis devices, in which peristaltic pumps are used for the transport of blood samples in the device or the washing process, etc.

However, peristaltic pumps have the disadvantage that variable delivery rates occur because of varying tube properties and wear of the tube. In particular, an undulation of the flow rate of the medium is produced in the tube by the mechanical engagement of the rolls with the tube and the displacement of the medium to be conveyed which thereby is caused, as can be seen in the chart of FIG. 2. Thus, the undulation constitutes a deviation from the average flow rate and temporarily brings about a higher or lower rate of flow depending on the position of the engaging rolls. The chart of FIG. 2 illustrates the temporal course of the flow rates v of the medium to be conveyed in μl/min for a peristaltic pump having two different tubes of the same type, but of different ages and different batch numbers, respectively. It is evident from the two measured curves M1, M2 that the flow rates indeed vary with the same period p (predetermined by the rotor speed and the distance between the rolls), but the amplitudes—and hence the undulations w—of the flow rates are clearly different in the two tubes. This influence of the tube properties and of the age of the tube is disadvantageous especially for blood analysis devices in which the tube is very often a consumer item and, together with other fluidic elements, is often integrated in a so-called fluid pack which is replaced at regular intervals. A further important characteristic of blood analysis devices is the possibility of using a blood sample volume as small as possible for the determination of analytes in order to put minimal stress on the patient. The attainment of this object is hampered by the undulation of the delivery rate of peristaltic pumps in blood analysis devices.

Various geometric structures of the outline of the pump body, to which the tube is applied, are known for reducing the undulation of the flow rate of peristaltic pumps. Reductions in the undulation of the delivery rate of approx. 10% are obtainable by such mechanical adaptations, and predominantly they are achieved by a more careful engagement of the squeezing rolls with the tube.

Another method of reducing the undulation of the flow rate of peristaltic pumps is a variation of the angular velocity of the rotor on which the squeezing rolls are mounted. This principle is described in document EP 389 719 B1. Therein, the peristaltic pump is provided with a determination of the position of the rolls. This may be, for example, an inductive or optical pulse generator on a roll. As soon as the roll equipped with the pulse generator passes a measuring point, a signal is emitted. Alternatively, if a stepping motor drives the rotor of the pump, a determination of position can be performed by the internal control of the stepping motor. Since the undulation of the flow rate of the peristaltic pump occurs periodically depending on the position of the rolls, said undulation is smoothed, i.e., reduced, by means of a motor-control in that the motor-control controls the motor driving the rotor by a change in the rotor's angular velocity which counteracts the undulation of the flow rate, depending on the position of the rolls. Thereby, the motor-control has to be adjusted such that it levels out a minimum undulation (in FIG. 2, this would be, for example, flow rate curve M2 with the smaller amplitude). The drawback is that a residual undulation remains for all pump configurations except for that with the minimum undulation.

As has already been mentioned, a demand for a sample volume which is as small as possible exists in many applications of peristaltic pumps, in particular, however, in blood analysis devices. In the current prior art, however, a proportion of the sample volume is required as a “tolerance volume”, which is necessary for levelling out the undulation of the flow rate. In the blood analysis device, the sample is positioned on a sensor which is for the respective determination of analytes and is arranged in the flow path of the sample, with the control of the sample positioning occurring on the basis of a defined constant flow rate. However, since the actual flow rate of the sample is not constant, but exhibits an undulation due to the properties of the peristaltic pump, it may happen that the sample stops ahead of or after the sensor, depending on the current flow rate. In order to avoid this uncertainty in the positioning of the sample, an enlarged sample volume having the above-mentioned tolerance-volume proportion must be provided.

SUMMARY OF THE INVENTION

It is against the above background that the present invention provides certain unobvious advantages and advancements over the prior art. In particular, the inventors have recognized a need for improvements in processes for peristaltic pump control.

Although the present invention is not limited to specific advantages or functionality, it is noted that the present invention provides a solution for the illustrated problems of the prior art. In particular, the undulation of the delivery rate of peristaltic pumps is reduced by the present invention, and a peristaltic pump control is provided which enables continuous calibration of a peristaltic pump during operation with regard to the flow rate and the undulation thereof. Thereby, the undulation of such peristaltic pumps is reduced which do not constitute a closed unit, but in which the tube is a replacement part or a consumption material which is replaced at relatively short intervals. After all, it should be possible by means of the present invention to reduce the required sample volume of the sample medium conveyed through peristaltic pumps in laboratory equipment, in particular blood analysis devices.

In accordance with one embodiment of the present invention, a process for controlling a peristaltic pump is provided and comprises measuring over time a fluidic parameter representative for the flow rate of the medium through the tube, determining the relative undulation of the flow rate of the medium from the measured temporal course of the fluidic parameter, and smoothing the undulation by adjusting the progression speed of the squeezing elements on the basis of the determined undulation of the flow rate.

These and other features and advantages of the present invention will be more fully understood from the following detailed description of the invention taken together with the accompanying claims. It is noted that the scope of the claims is defined by the recitations therein and not by the specific discussion of features and advantages set forth in the present description.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of the embodiments of the present invention can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:

FIG. 1 shows the schematic structure of a peristaltic pump;

FIG. 2 shows a diagram of two temporal courses of flow rates of a medium conveyed in a peristaltic pump according to the prior art before and after the replacement of the tube;

FIG. 3 shows a block diagram of an arrangement of a peristaltic pump having a pump control according to the invention and means for detecting fluidic parameters according to the present invention; and

FIG. 4 shows a specific arrangement for detecting fluidic parameters according to the present invention.

Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of the embodiment(s) of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

According to the invention, every measurand suitable for measuring or detecting changes in the flow rate through the tube of the peristaltic pump is provided as a fluidic parameter.

The solution according to the invention is based on the principle that the undulation of the flow rate can be leveled out or at least reduced by adjusting the progression speed of the squeezing elements of the peristaltic pump, depending on the current position of the squeezing elements. Thereby, the invention additionally takes into account that the undulation of the flow rate may change if the tube of the peristaltic pump is replaced and/or due to the aging of the tube. To this end, the invention envisages that the variation of the progression speed of the squeezing elements of the peristaltic pump, which is necessary for smoothing the undulation of the flow rate, is adapted to the current tube properties by a recurring calibration during running operation and an appropriate adjustment of the control of the rotational speed of the rotor. Thus, the invention is suitable for use in peristaltic pumps which do not form an inseparable unit, but in which the tube has to be replaced again and again as a consumption material.

The invention is suitable for use in classical, simple peristaltic pumps with a constant speed of the squeezing elements, which has been preset in the factory, and also in peristaltic pumps which are calibrated in the factory to particular tube properties by presetting a periodical variation of the progression speed which depends on the position of the squeezing elements. In the latter peristaltic pumps, the undulation is smoothed by adjusting the preset periodical variation of the progression speed of the squeezing elements on the basis of the relative undulation of the flow rate which has been determined.

In a typical embodiment of the invention, which can be implemented easily, the adjustment of the periodical variation of the progression speed of the squeezing elements comprises calculating a calibration factor from the determined undulation of the flow rate of the medium and readjusting the periodical variation of the progression speed of the squeezing elements by the calibration factor.

In order to be able to detect and optionally compensate for changes in the properties of the peristaltic pump, in particular caused by the aging of component parts etc., during running operation, in one embodiment of the invention it is envisaged to check the calibration factor (or the determined undulation of the flow rate as a quantity associated therewith) during running operation to find out if it lies within predetermined limits and to conduct a recalculation of the calibration factor if those limits are exceeded, which will result in an adaptation of the periodical variation of the progression speed of the squeezing elements.

The invention is suitable for use in all types of peristaltic pumps, for example, the initially mentioned types, in which the tube is linear or arranged along any desired predetermined path. The squeezing elements may be arranged, for example, along the tube in the form of a “piano keyboard” while being movable individually by actuators or may be moved jointly by an actuator such as a linear drive or by a band driven by a conveyor belt.

In another embodiment which is very reliable and compact, the actuator is a rotor driven by a motor, from which rotor the squeezing elements are moved in a circular motion along the tube, whereby the position of the squeezing elements is detected during the rotation of the rotor and the progression speed of the squeezing elements is adjusted by controlling the angular velocity of the rotor.

In yet another embodiment of the present invention which can be implemented with inexpensive standard components, the flow rate of the medium is measured as a fluidic parameter by detecting the time period required by medium packages or by the front and end of the medium or by the front and end of medium packages for passing with a constant measuring volume through a measuring section located in the flow path of the peristaltic pump. At the same time, the positions of the squeezing elements are detected and allocated to the time periods, resulting in a curve of the relative undulation of the flow rate.

The medium packages are typically generated by introducing air bubbles into the medium flow, with the medium flow originating either from a sample medium or a calibration liquid, for example, a calibration liquid, a quality control liquid or a washing liquid of a blood analysis device. In order to avoid measuring artifacts, it is envisaged to introduce the air bubbles into the medium flow at irregular intervals.

In order to detect individual values of the curve of the undulation within a period instead of obtaining a mean value measurement, the measuring volume of the measuring section and the size of the medium packages are chosen such that the period of the undulation of the flow rate which corresponds to the distance between adjacent squeezing elements and the progression speed of the squeezing elements, in particular to the angular velocity of the rotor, is a multiple of the time period required by the medium packages for flowing through the measuring section.

A precise and quick measurement of the duration of the passing of the medium packages through the measuring section is typically achieved by using optical sensors.

As an alternative to the measurement of the undulation of the flow rate by means of medium packages, a defined measuring section and a time measurement, other fluidic parameters can also be used for measuring the undulation, namely in particular the pressure of the medium which is detected by a pressure sensor, or the temperature of the medium which is detected by a temperature sensor, or the flow rate of the medium itself which is detected by a flowmeter. The medium can also be guided into a weighing cell, wherein the relative weight change of said weighing cell is the fluidic parameter. Alternatively, the electrical conductivity of the medium can be measured as a fluidic parameter by a conductivity sensor.

Furthermore, basically all measurands which are suitable for measuring or detecting changes in the flow rate through the tube of the peristaltic pump can be used as possible fluidic parameters. Thus, for example, indirect measurands can also be used, which in turn depend on further measurands which respond in a characteristic way to changes in the flow rate through the tube of the peristaltic pump.

In one aspect of the invention, it is envisaged to perform the process for controlling a peristaltic pump after every exchange of the tube in order to adequately consider the modifications of flow parameters, etc., during the operation of the pump, which may have been caused by the replacement of the tube. This aspect of the invention is important especially for peristaltic pumps in which the tube is designed as a replacement part or is integrated in such a part.

In order that the invention may be more readily understood, reference is made to the following examples, which are intended to illustrate the invention, but not limit the scope thereof.

The basic structure of a peristaltic pump 1 is now explained on the basis of the illustration of FIG. 1. The peristaltic pump 1 comprises a rotor 3 which is driven by a motor 2 toward a rotation in the direction of arrow r. On its circumference, the rotor 3 comprises squeezing elements 4 which are spaced apart at equal distances and, in this embodiment, are designed as rolls. Alternatively, the squeezing elements 4 might be designed as sliding elements. The rotor 3 is embraced by a tube 5 at an angle of approx. 180°, which, on its outside, is supported on a body structure 6. With a rotation of the rotor 3, the squeezing elements 4 successively get into and out of a squeezing engagement with the tube 5, whereby a negative pressure is produced at the inlet 5 a of the tube 5, which negative pressure sucks a medium 7 to be conveyed through the peristaltic pump, such as, e.g., a blood sample or a rinsing liquid, into the tube 5, transporting it through the tube 5 as far as to the pump outlet 5 b. With a uniform rotation of the rotor 3, the corrugated course of the flow rate v of the medium 7 as illustrated in the chart of FIG. 2 appears, wherein, in the chart of FIG. 2, the undulation w can be determined as the peak-peak-difference of the amplitude of each period p. The period p of the undulation w in turn results from the angular velocity r of the rotor 3 and the distance between adjacent squeezing elements 4. Each time a squeezing element 4 starts to engage the tube 5, a new period p starts which lasts until the next squeezing element 4 engages the tube 5. As has been described initially, with regard to smoothing the undulation w, it is known from the prior art to control the motor 2 such that the rotor 3 varies its angular velocity r within each period p in such a way that it counteracts the undulation. For this purpose, it is necessary to know the position of the squeezing elements 4 during the rotation of the rotor, for which, for example, a position sensor 8 may be provided. If the motor 2 is designed as a stepping motor, it is also possible to detect the position of the squeezing elements 4 from the step sequence of the motor.

As far as it has been described up to now, the peristaltic pump 1 is known from the prior art. However, without the control and calibration according to the invention, which are to be described below, it would display a fairly smooth delivery behaviour only for a tube 5 with precisely defined properties, even if the known variation of the angular velocity r of the rotor is provided. However, since every tube 5 changes its properties in the course of its lifetime due to wear and environmental impacts and, in case the tube 5 is exchanged, a replacement by a tube with identical properties is hardly possible, the delivery behaviour would in practice exhibit the known undulations of the flow rate of the medium. However, by the measures according to the invention, the undulation of the flow rate of a medium 7 conveyed through the tube 5 can be kept permanently at a minimum.

FIG. 3 shows a block diagram of an arrangement of the peristaltic pump 1 of FIG. 1 comprising a pump control 12 according to the invention and measuring equipment 10 for detecting fluidic parameters according to the present invention. The peristaltic pump 1 is equipped with a position sensor 8 for detecting the exact position of the squeezing elements 4 of the rotor 3. The pump control 12 is designed for periodically varying the angular velocity of the rotor 3 according to a predetermined course, depending on the position of the squeezing elements 4, so that a base reduction of the undulation of the flow rate v of a medium 7 conveyed through the tube 5 is achieved. The predetermined course of the periodical variation of the angular velocity of the rotor 3 can be stored, for example, in a table in a memory of the pump control 12. Said table is created, for example, during the assembly of the pump 1 by detecting the course of the flow rate of the medium through the tube 5 with a uniform rotation of the rotor 3 and calculating a compensating curve which counteracts the undulation of the flow rate and is stored in the memory of the control 12 in the form of said table.

However, such a compensating curve or table, respectively, is valid only at the time of its generation and at the conditions and material properties which exist at that time. In the course of time, it will deviate more and more from the actual requirements. Therefore, the invention provides calibration means 11 which are designed, e.g., as a microprocessor and recalibrate the pump control 12 at certain time intervals. The time intervals of the calibration can either be event-driven, e.g., every time the tube 5 is replaced, or can be determined in a time-controlled manner on the basis of predetermined intervals. For the calibration, the calibration means 11 detect a fluidic parameter FP which is representative for the flow rate v of the medium and is measured by means of the measuring equipment 10. The calibration means 11 then determine the undulation of the flow rate of the medium from the measured fluidic parameter FP (cf., chart of FIG. 2) and readjust the periodical variation of the angular velocity r of the rotor 3, which has been caused by the pump control 12, on the basis of the determined undulation of the flow rate in such a way that it will counteract the undulation of the flow rate, thus reducing it. More precisely, the basic course of the variation of the angular velocity of the rotor is maintained due to this change in the pump control 12, but the absolute values and the amplitude, respectively, are adjusted. In a typical embodiment of the invention, this is achieved by multiplying the prestored course of the variation of the angular velocity in the pump control 12 by a calibration factor KF which is calculated by the calibration means 11 depending on the detected undulation w of the flow rate v and is transmitted to the pump control 12. Said calibration process may be repeated iteratively until the desired smoothing of the undulation is achieved. The course of the variation of the angular velocity of the rotor 3 resulting therefrom is maintained until a new calibration is performed.

In order that no sample medium 17 has to be wasted for the calibration of laboratory equipment such as blood analysis devices, a fluid switch 13 can be arranged upstream of the peristaltic pump 1, which, during normal operation, supplies the pump with the sample medium 17 as a medium 7 to be conveyed and, for the calibration, delivers a calibration liquid 14, which, for example, is a rinsing liquid. For the generation of individual liquid medium packages 14 a, a valve 16 is provided in the path of the calibration liquid 14, by means of which valve air 15 can be introduced in order to generate in this way individual medium packages 14 from the flow of calibration liquid 14, as will be explained in further detail below.

A collection container 18 for the medium 7 is provided downstream of the means 10 for detecting a fluidic parameter.

The means 10 for detecting a fluidic parameter FP may be based on various sensory principles, in particular on physical principles. In one embodiment, the fluidic parameter FP is the pressure of the medium 7, with the detection means 10 being designed as a pressure sensor.

In an alternative embodiment, the fluidic parameter FP is the temperature of the medium 7, with the detection means 10 being designed as a temperature sensor.

In a further embodiment, the fluidic parameter FP consists in the relative weight changes of a weighing cell into which the medium 7 is introduced. For this purpose, for example, the weight of the collection container 18 is constantly determined, with the detection means 10 being designed as a balance.

In a further alternative embodiment, the fluidic parameter is the flow rate of the medium, with the detection means 10 being designed as a flowmeter.

In a further embodiment, the fluidic parameter FP is the electrical conductivity of the medium 7, with the detection means 10 being designed as a conductivity sensor.

On the basis of the schematic illustration of FIG. 4, an embodiment of the detection means 10 is now described which measures the time required by medium packages 14 a for flowing through a constant measuring section MS.

The measuring section MS is located in the fluidic path of the peristaltic pump, e.g., in the tube 5 or in a conduit located downstream thereof. The measuring section MS has a constant volume, which, however, is possibly unknown due to component tolerances. Said measuring section MS is delimited by two optical sensors S1, S2, which are able to identify medium packages 14 a and their beginnings and ends, respectively, during running operation. Those medium packages are generated by switching the fluid switch 13 (see FIG. 3) to the supply of calibration liquid 14 and introducing air 15 in a temporal sequence through the valve 16 into the calibration liquid 14. In order to avoid measuring artifacts, it is envisaged that the medium packages 14 a have different volumes and/or different distances between each other. The residence time of the medium packages 14 in the measuring section is measured and plotted into a table or chart depending on the position of the squeezing elements. The process is repeated with several medium packages 14 a, which results in a table or curve, respectively, of the relative undulation depending on the position of the squeezing elements. The length of the measuring section MS is to be chosen such that the time required by each medium package 14 a for passing through the measuring section MS is only a fraction, e.g., less than a fifth of the period duration p of the undulation w of the peristaltic pump 1. In this way, it can be achieved that not only a mean value of the flow rate v, but an individual value is determined within a period p of the undulation w. The control of the fluid switch 13 and of the valve 16 is effected via the calibration means 11 which are supplied with the duration of the passing of the medium packages 14 a through the measuring section MS as a fluidic parameter FP and simultaneously are supplied with the exact positions of the squeezing elements 4 by the position sensor 8 and are thus able to create the above-mentioned table or curve, respectively, of the relative undulation. Thereupon, a calibration factor KF is calculated by means of the table and supplied to the pump control 12 which changes the absolute values and the amplitude, respectively, of the periodically varying angular velocity of the rotor on the basis of the determined calibration factor KF. With this changed activation of the peristaltic pump 1, medium packages 14 are again measured in the measuring section MS. As a result of the change in the calibration factor of the pump, the table values change as well. In an optimization cycle, the control 12 of the peristaltic pump 1 can thus be calibrated with every tube exchange and for every operating state, respectively, or at regular intervals. Upon completion of the calibration, the fluid switch 13 is switched into the position in which the sample medium 17 is supplied to the peristaltic pump 1.

It is noted that terms like “preferably”, “commonly”, and “typically” are not utilized herein to limit the scope of the claimed invention or to imply that certain features are critical, essential, or even important to the structure or function of the claimed invention. Rather, these terms are merely intended to highlight alternative or additional features that may or may not be utilized in a particular embodiment of the present invention.

For the purposes of describing and defining the present invention it is noted that the term “substantially” is utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The term “substantially” is also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.

Having described the invention in detail and by reference to specific embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims. More specifically, although some aspects of the present invention are identified herein as preferred or particularly advantageous, it is contemplated that the present invention is not necessarily limited to these preferred aspects of the invention. 

1. A process for controlling a peristaltic pump comprising squeezing elements moved by at least one actuator, which squeezing elements act on a tube in which a medium is conveyed, with the squeezing elements successively getting into and out of a squeezing engagement with the tube, characterized by: measuring over time a fluidic parameter representative for the flow rate of the medium through the tube, determining the relative undulation of the flow rate of the medium from the measured temporal course of the fluidic parameter, and smoothing the undulation by adjusting the progression speed of the squeezing elements on the basis of the determined undulation of the flow rate.
 2. The process according to claim 1, characterized in that in peristaltic pumps with a periodical variation of the progression speed of the squeezing elements, which has been preset particularly in the factory, depending on a current position of the squeezing elements, smoothing of the undulation is performed by adjusting the preset periodical variation of the progression speed of the squeezing elements on the basis of the relative undulation of the flow rate which has been determined.
 3. The process according to claim 1, characterized in that the adjustment of the periodical variation of the progression speed of the squeezing elements comprises calculating a calibration factor from the determined undulation of the flow rate of the medium and readjusting the periodical variation of the progression speed of the squeezing elements by the calibration factor.
 4. The process according to claim 3, characterized in that the calibration factor is checked during running operation to find out if it lies within predetermined limits and a recalculation of the calibration factor is conducted if those limits are exceeded.
 5. The process according to claim 1, characterized in that the actuator is a rotor driven by a motor, from which rotor the squeezing elements are moved in a circular motion along the tube, whereby the position of the squeezing elements is detected during the rotation of the rotor and the progression speed of the squeezing elements is adjusted by controlling the angular velocity of the rotor.
 6. The process according to claim 1, characterized in that the fluidic parameter is the flow rate of the medium and is measured by detecting the time period required by medium packages or the front and end of the medium or of medium packages, respectively, for passing with a constant measuring volume through a measuring section located in the flow path of the peristaltic pump, simultaneously detecting the positions of the squeezing elements and allocating the positions of the squeezing elements to the time periods, resulting in a curve of the relative undulation of the flow rate.
 7. The process according to claim 6, characterized in that the medium packages are generated by introducing air into a medium flow, in particular that the air is introduced into the medium flow at irregular intervals.
 8. The process according to claim 6, characterized in that the measuring volume of the measuring section and the volumes of the medium packages are chosen such that the period of the undulation of the flow rate which corresponds to the distance between adjacent squeezing elements and the progression speed of the squeezing elements, in particular to the angular velocity of the rotor, is a multiple of the time period required by the medium packages for flowing through the measuring section.
 9. The process according to claim 6, characterized in that the passing of the medium packages through the measuring section is detected by optical sensors.
 10. The process according to claim 1, characterized in that the fluidic parameter is the pressure of the medium and is detected by a pressure sensor, or the fluidic parameter is the temperature of the medium and is detected by a temperature sensor, or the fluidic parameter is the relative weight change of a weighing cell into which the medium is introduced, or the flow rate is detected by a flowmeter, or the fluidic parameter is the electrical conductivity of the medium and is detected by a conductivity sensor.
 11. The process according to claim 1, characterized in that it is performed after every exchange of the tube, with the tube being designed as a replacement part or being integrated in a replacement part. 